German Patent Publication No. DE 41 29 577 discloses a measuring system for detecting angles of rotation where it is possible to modify measuring system-specific data by the operator. The measuring system includes a data memory, which is connected by signal transmission lines with an evaluation unit. The measuring system can be programmed to be user-specific by the temporary connection of the measuring system outputs or the memory outputs with the transmission lines. A time-sequential multiplex method is proposed for the data transmission, which represents a relatively technically elaborate solution. The synchronization between the measuring system and the evaluation unit is furthermore not assured. In addition, the proposed interface is not universally usable with different measuring systems, for example, for measuring systems which already provide the actual measured value in the form of an absolute position and where the measured value of interest does not have to be generated in the evaluation unit downstream.
European Patent Publication No. EP 0 171 579 discloses a device as well as a method for synchronous-serial data transmission between a transducer and a processing unit. The proposed device includes a clock signal transmission line as well as a data signal transmission line through which the transducer and a downstream connected processing unit are connected with each other. The clock signal transmission line and data signal transmission line are only uni-directionally operated. User-specific programming of the transducer, for example, by writing/reading to or from memory units which are associated with the transducer is not provided or possible with this device.
For this reason it is suggested in European Patent Publication No. EP 0 660 209 to embody at least one signal transmission line between the transducer and the processing unit to be bi-directional and to assign the transducer a number of memory sectors. The user can write/read to or from the memory sectors by this signal transmission line so that it is possible for the user to adapt the processing unit to specific transducer parameters. The memory sectors can contain the most diverse parameters of the transducer, for example, information regarding its operational state, parameters of the processing unit, etc. Selective programming or measuring operation is possible with the aid of such a device. However, this advantageous solution requires certain prerequisites on the part of the transducer, in particular a bi-directional signal transmission line to the processing unit, and for this reason it cannot be universally employed, for example, in connection with transducers which have clock and data lines which can only be uni-directionally operated.
European Patent Publication No. EP 0 324 067 discloses another design of an interface between a transducer and a downstream arranged processing unit. Here, too, read/write memory units assigned to the transducer are provided in which characteristic transducer data are stored. This solution, like the previously described variant, can only be employed in connection with transducers designed for this and with a corresponding layout of the signal transmission lines.
Furthermore, U.S. Pat. No. 4,831,380 discloses an interface for transducers where the simultaneous transmission of transducer correction data and measured data to the processing unit takes place by way of the detection of a reference signal. However, there is no teaching of a programming of the transducer or switching between different operating modes of the transducer.